$ ls
hello
$ perl -e 'my $dir = q(not$socooldir); system "mkdir $dir" and die "execution failed\n"'
$ ls
hello  not
$ perl -e 'my $dir = q(not$socooldir); $dir = quotemeta $dir; system "mkdir $dir" and die "execution failed\n"'
$ ls
hello  not  not$socooldir
$ perl -e 'my $dir = q(not$socooldir); system "mkdir \Q$dir" and die "execution failed\n"'
mkdir: cannot create directory `not$socooldir': File exists
execution failed